The present invention relates to a control system and method for a vehicle generator, particularly of the kind capable of attaining improved vehicle acceleration ability, improved fuel consumption and suitable power supply in accordance with a loaded condition of the generator.
A vehicle generator is connected to a rotational shaft of an engine and is therefore caused to vary in rotational speed over a wide range. For this reason, the vehicle generator is provided with a regulator (control system) for regulating generated voltage within a suitable range. The regulator of this kind controls the generated voltage by intermittently operating the generator through ON/OFF control of the field current of the generator. When the load on the generator becomes larger, the generation time is controlled so as to become longer for maintaining the generated voltage constant.
In recent years, electrical equipments installed on a vehicle are increasing in number sharply, thus increasing the required electric power. In response to this, a generator has a tendency to becoming larger in size. However, a large-sized generator applies a large load to an engine when in operation, thus resulting in deterioration in acceleration ability and fuel consumption of a vehicle. On the other hand, it is desirable to perform power generation positively upon deceleration of the vehicle for thereby promoting engine braking while regenerating a battery.
However, the conditions under which the vehicle electrical equipments are used vary largely depending upon whether it is used in the daytime or night, or the season it is used. If the power generation time is shortened for the purpose of improving the acceleration ability and fuel consumption, there will be caused a problem of overdischarge of the battery and flickering of lamps when the working power is large. On the contrary, if the power generation time is made longer upon deceleration of the vehicle, there will be caused a problem of overcharge of the battery and burning out of lamps.
To solve such problems, it has been proposed a regulator for adequately controlling the power generation time during which power is generated, in accordance with the load on the generator as disclosed in Japanese Patent Provisional Publication No. 4-63639. The regulator controls the power generated by the generator in relation to acceleration and deceleration of the vehicle and vehicle speed thereby reducing the power generation torque allotted to the engine and improving the acceleration ability and fuel consumption of the vehicle.
However, the above described regulator is constructed so as to execute a control for reducing the generated power for the purpose of improving the acceleration ability and fuel consumption of the vehicle, while at the same time inhibiting the above described control when certain electrical equipments are turned on or when the value of current detected by a current detector becomes equal to or higher than a predetermined value for the purpose of preventing a variation of performance of electrical equipments due to a variation of generated voltage, for example, flickering of lamps.
For this reason, the above control is inhibited at almost all the time when there is actually a passenger on a vehicle, resulting in a problem that the regulator cannot contribute to improvement in the acceleration ability and fuel consumption of the vehicle.
It is accordingly an object of the present invention to provide a control system for a vehicle generator that can improve vehicle acceleration ability and improved fuel consumption while being capable of realizing suitable supply of power to vehicle electrical equipments according to the loaded condition of the generator.
To achieve the above object, there is provided according to an aspect of the present invention a control system for a vehicle generator comprising a first detector for detecting a running condition of a vehicle and producing a signal representative thereof, a second detector for detecting whether vehicle electrical equipments are ON or OFF, and a controller responsive to the signals from the first detector and the second detector for controlling a field current of the generator thereby controlling an output voltage of the generator, wherein the controller is programmed to send to the generator, if the vehicle electrical equipments are OFF and the vehicle is in a running condition other than a decelerating condition, a generation command value that is a first target voltage lower than a normal generation voltage, send to the generator, if the electrical equipments are OFF and the vehicle is in the decelerating condition, a generation command value that is a second target voltage higher than the normal generation voltage, and send to the generator, if one of the electrical equipments is ON, a generation command value that is a third target voltage lower than the normal generation voltage and higher than the first target voltage.
According to another aspect of the present invention, there is provided a control method for a vehicle generator comprising detecting a running condition of a vehicle and producing a first signal representative thereof, detecting whether vehicle electrical equipments are ON or OFF and producing a second signal representative thereof, and controlling, in response to the first and second signals, a field current of the generator thereby controlling an output voltage of the generator, wherein the controlling of the field current of the generator including sending to the generator, if the vehicle electrical equipments are OFF and the vehicle is in a running condition other than a decelerating condition, a generation command value that is a first target voltage lower than a normal generation voltage, sending to the generator, if the electrical equipments are OFF and the vehicle is in the decelerating condition, a generation command value that is a second target voltage higher than the normal generation voltage, and sending to the generator, if predetermined one of the electrical equipments is ON, a generation command value that is a third target voltage higher than the first target voltage.